Information carriers, method of forming and copying said carriers

ABSTRACT

An original information carrier is disclosed which comprises a recording layer applied to a carrier material. The recording layer contains information in the form of a relief image which is made of relief part-images which border on one another without overlapping. The recording layer further comprises a relief grating of different grating depths superimposed over the areas of said relief part-images. 
     A process for producing an information carrier is disclosed which comprises exposing a recording layer through separate color separation originals, exposing the layer to a grating pattern, and developing the exposed recording layer. 
     A process for forming a matrix containing the information stored on an information carrier is disclosed which comprises forming a layer of material on the original information carrier and then separating the layer from the carrier. The separated layer of material may then be used to make additional copies of the original relief image by contacting it with transparent deformable materials. 
     Also, an information carrier which is a copy of an original information carrier is disclosed which is made of a deformable material having the relief gratings and part-images of the original embossed therein.

This is a division of application Ser. No. 861,491, filed Dec. 16, 1977.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an information carrier and processes forproducing an original copy of the carrier, which comprises a recordinglayer deposited on a carrier material. A relief image containing theinformation is embossed in the recording layer.

2. Description of the Prior Art

Images with grating-like screening have been produced by the ZOD (zeroorder diffraction) technique described in the LASER u. Elektro-OptikJournal No. 3/1976, pages 16-17. Three nickel matrices are produced fromthe relief images which correspond, for example, to three primary-colorgrating patterns in a photoresist, and colorless thermoplastic films of,for example, polyvinyl chloride are embossed with these matrices. Thesefilms are mechanically superimposed, and, on projection withconventional projectors, colored projection images are obtained from thecolorless relief images. The grating-shaped screening is effected withrelief gratings of rectangular cross-section, the grating periods beingapproximately 1.5 μm. A separate nickel matrix with different reliefdepths is made for each color separation (red, yellow and blue), fromwhich separate embossed images are produced. The relief depths differdepending on the color separation. The greatest relief depths are usedfor the red color separation while the smallest are used for the bluecolor separation. The color separation images are screened. The embossedimages are then superimposed to form a three-layered relief image whichcan be used to project colored images. The technique described yieldsvery bright color images with high resolution. The relief images can beduplicated relatively cheaply and rapidly by an embossing process.

A disadvantage, which has hindered the introduction of this technique,is the expansive production process, incurred by performing threecompletely separate operations for producing the individual, embossedrelief images, corresponding to the color separations. A furtherdisadvantage ensues from the necessity of aligning the three separaterelief images to form the duplicate image required for the coloredprojection.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an original or initialinformation carrier which overcomes the above deficiencies of the priorart.

It is a further object of the invention to provide a process of makingthe improved information carrier of the invention.

It is yet another object of the invention to disclose a matrix which maybe used to reproduce the information stored on the initial or originalinformation carrier.

It is yet another object of the invention to provide a process forforming and using the matrix to emboss the original information onto adeformable transparent material to form duplicate copies of theoriginal.

In accordance with the invention, an information carrier has beendeveloped which comprises a recording layer applied to a carriermaterial. The recording layer contains information embossed therein inthe form of a relief image. The relief image comprises reliefpart-images which border on each other without overlapping. Therecording layer further comprises a relief grating having differentgrating depths superimposed on the areas of said relief part-images.

The process for producing an original copy of an information carriercomprises exposing a recording layer mounted on a carrier throughseparate color separation originals to form relief part-images. Theoriginal is transparent in the areas of the particular projection colorsof the color separation originals. The recording is also exposed to agrating pattern separately from the other exposure to form reliefpart-images. The doubly exposed recording layer is then developed.

The invention also makes it possible to reproduce the information storedon an information carrier. In such a process, a recording layer, havinginformation therein in the form of a relief image and comprising arelief grating having different grating depths, is coated with a thinelectrically conductive layer which is electroplated onto it. A metallayer is then deposited on the electrically conductive layer so that themetal coating layer represents the negative relief image of therecording layer. The metal coating or matrix is then separated from therecording layer.

Furthermore, as information carrier is disclosed which comprises anembossable layer having information embossed therein in the form of arelief image. The relief image is composed of relief part-images whichborder but do not overlap each other. The layer further comprises arelief grating superimposed over the areas covered by the individualrelief part-images.

Finally, the invention includes a process of embossing a deformabletransparent material by applying the matrix of the invention to adeformable transparent material to produce a relief image on thetransparent material. After the relief image is formed, the matrix layeris separated from the deformable material.

An important feature of the invention is that the relief image iscomposed from the superposition of the relief part-images correspondingto the individual color separations, in such a way that areas ofdifferent colors, which when using screened images may also be screenpoints, at the most touch, but do not overlap one another.

BRIEF DESCRIPTION OF THE DRAWINGS

As illustrated in the drawings:

FIGS. 1a, b, c, and d show an original copy of an information carrier incross-section, in the various process stages of production;

FIGS. 2a and b show another embodiment of an original copy of aninformation carrier in cross-section at the beginning and at the end ofproduction;

FIG. 3 shows a planar view of an original copy with test areas; and

FIG. 4 shows a planar view of an original copy having register marks foralignment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Experiments may be run to investigate the properties of photoresistlayers having thicknesses varying between 0.95 and 2.10 microns ontransparent films. Four samples are selected in which the photoresistlayers have thicknesses of 0.95 microns, 1.34 microns, 1.72 microns and2.10 microns. The thicknesses of the layers can be determined by meansof an interference microscope on flaked-off portions of the layers. Thesample layers are brought into contact with an original grating and areirradiated through the grating with actinic light. Parallel light from a200 watt mercury high-pressure lamp may, for example, be used. The lightpasses through a quartz lens having a focal length of 15 cm. and thenthrough a blue glass filter having a maximum transmission of 75% of thelight intensity at a wave length of 400 nm. The grating original is, forexample, a glass plate with transparent areas and areas made opaque bybeing covered with metal strips. The period of the grating is 138lines/mm. After various exposure times the samples, which are developedwith aqueous alkaline developer, are irradiated with white xenon light.Bright, colored diffraction images appear. The transmitted undiffractedlight exhibits the following colors:

    ______________________________________                                        Exposure                                                                      time   Thickness of the photoresist layer                                     (seconds)                                                                            0.95 μm                                                                              1.34 μm 1.72 μm                                                                             2.10 μm                               ______________________________________                                        0      pale-yellow/brown                                                                              (intrinsic color of the                                                       photoresist)                                          20     yellowish yellowish  yellowish                                                                              yellowish                                30     blue      blue       blue     blue                                     40     light     intense    intense  intense                                         green     yellow     yellow   yellow                                   50     light     pale       intense  intense                                         green     magenta    magenta  magenta                                  60     light     pale       pale     intense                                         green     magenta    magenta  cyan                                     70     light     pale       pale     light                                           green     magenta    magenta  green                                           with      with yellow                                                         bluish    patches                                                             patches                                                                ______________________________________                                    

Intense projection colors are thus seen to occur with the followingrelief depths:

    ______________________________________                                        yellow:       between 0.95 μm and 1.34 μm                               magenta:      between 1.34 μm and 1.72 μm                               cyan:         between 1.72 μm and 2.10 μm                               ______________________________________                                    

If, for example, a dark blue tending towards violet, and having awavelength λ_(B) of 410 nm, is to be reproduced, it is necessary thatthe relief depth of the recording layer be about three times the valueof the wavelength of the complementary color, namely yellow, awavelength λ_(Y) of 580 nm, that is to say, 3λ_(Y) =1740 nm=1.74 μm.

The threefold values of the wavelengths of light of the particularcomplementary colors lie within the specified relief intervals. Thesethreefold values for yellow/magenta/cyan amount to approximately 1.26μm, 1.59 μm and 1.83 μm.

The production of the relief part-images with grating-like screening, inthe photoresist layer, and in particular the exposure of the photoresistlayer, are essential steps in the process of the invention. Thesubsequent production of a metal matrix and the embossing of thethermoplastic film are effected by known techniques.

For the reproduction of the cyan color, the photoresist layer providedmust be at least about 1.83 μm thick, preferably between 2 μm and 3 μm.The essential factor in this process is the uniformity of the layerthickness. For small areas up to about 1 dm² a homogeneous coating isobtained by dipping and slowly withdrawing the carrier of thephotoresist layer out of the coating solution. Alternatively, thecoating solution can be applied on a rotating carrier material. The edgeregions frequently exhibit a ridge of photoresist and are therefore notused. Variations in the layer thickness can, with careful coating, bekept to below 0.1 μm. Glass plates are preferred for use as carriers forthe photoresist layer because of their planar surface and the relativelysimple manner in which they may be cleaned before coating. Nevertheless,films and metal carriers may also be used.

A line-by-line exposure technique can be employed in which, for example,a laser beam with a line spacing corresponding to the grating structureis passed over the photoresist layer with image-wise modulation of theintensity. Alternatively, an exposure technique using color separationsof the information to be reproduced in color can be employed.

By way of example, in the process utilizing color separations, theexposure of the photoresist layer, with the image information, and thegrating exposure are carried out separately at different times. In thisprocess first the image-wise exposure is carried out and then thegrating exposure. Although this sequence is preferred, it is notabsolutely necessary.

EXAMPLE 1

FIG. 1a shows a still unexposed photoresist layer 2 on a carrier layer 1of glass, film or metal (not drawn to scale). This is exposed throughthe color separation originals 3, 4 and 5 in such a manner that theimage areas of unexposed photoresist which remain have a thickness ofabout t₁ =1.26 μm under the color-separation original 3 for a yellowprojection color; a thickness of about t₂ =1.59 μm under thecolor-separation original 4 for a magenta-colored projection color; anda thickness t₃ of about 1.83 μm under the color-separation original 5for a cyan projection color, as indicated in FIG. 1b. Separatecolor-separation originals can be used, in which case the individualcolor-separation originals must be glass-clear in the area of theparticular projection color desired, and must cover in the remainingareas. The particular thickness of the still unexposed photoresist layeris measured very carefully during the exposure in order to end theexposure as soon as the desired residual thickness of photoresist isreached. The determination of the change in optical density in thespectral range of absorption of the light-sensitive compound in thephotoresist is a rapid, and to a great extent inertialess, method ofmeasurement. For example, o-quinone-diazides, which are often containedin so-called positive working photoresists, have an absorption maximumat a wavelength of 407 nm. An optical density of 0.824 has been measuredon an approximately 3 μm thick photoresist layer and an optical densityof 0.072 has been measured on the exposed photoresist layer. The finalvalue represents the optical density of the photolysis product formedduring the exposure and is taken into account to correct the opticaldensity of the thickness of the unexposed photoresist layer. Thisexample shows that the measurement of the optical density with atechnically possible accuracy of 0.01, and better, permits measurementof the thickness of the unexposed photoresist layer with an accuracy of0.1 μm and higher. The optical measurement for checking the thickness ofthe unexposed photoresist layer provides a relevant indication of thethickness of the photoresist which has not as yet been alteredphotochemically, since in the photoresist layers, which in thephotographic sense are of very high contrast, the particular surfacelayer of non-decomposed o-quinone-diazide facing the light source isconverted photochemically and is dissolved away on development.

It is advantageous, with respect to the optical check on the thicknessduring the exposure, to provide test areas 8, 9 and 18 on thephotoresist layer 2, as represented in FIG. 3, adjacent to the actualrelief image 10, for the exposures corresponding to the various colorseparation originals 3, 4 and 5.

The intensity distribution of the irradiated actinic light must beconstant over the recording area, with variations being, to the extentpossible, below one percent. It may, moreover, be necessary to provideempirical corrections for the settings of the optical densities, forexample, in order to match the activity of the developer.

The exposures through the color-separation originals are carried out byknown techniques, for example. For this purpose, aids such as mechanicalguides or microscopic control of the coincidence of marks on thephotoresist layer 2 and the color separation original, are required foraligning the color separations, particularly when the latter arescreened. With mixed colors, the screen points of the various colorseparations must not overlap. High resolution, UV-corrected objectivesfor the exposure of photoresist layers or semiconductor substrates areknown. With such objectives, the color-separated exposure can beeffected in projection, with change of scale, if required.

The values of the layer thicknesses of the undecomposed resist for thedifferent colors can be taken into consideration in the production ofthe color-separation originals by matching the optical densities of thecolor-separation originals, combined on a single photographic film, insuch a manner that, with a given thickness of the photoresist layer, thethicknesses of undecomposed photoresist in the layer, corresponding tothe projection colors, are obtained during a single exposure.

In general, the grating exposure is effected after the image-wisecolor-separation exposure, without intervening development and thisleads to a structure according to FIG. 1d in which the photoresist layer2 is exposed through to the carrier layer 1, and various grating depths13, 14 and 15 are obtained after development. The relief image 10 iscomposed of the relief part-images 3', 4' and 5', which border on oneanother without overlapping. The exposure can be carried outadvantageously with interfering UV laser beams which cross one another.In this way, grating periods of 1/500 mm, and smaller can be producedwithout difficulty. The desired rectangular grating structure is formed,to a good approximation, by the high-contrast photoresist. In the caseof smaller periods, the grating structure can be impressed by theformation of periodic grating-pattern originals using high-resolution,UV-corrected objectives. Contact exposures under very accurate gratings17, for example metal gratings on glass plates, which are availablecommercially for periods of 1/10 mm to 1/1000 mm, have also provenuseful. As with all contact exposures it is advantageous to introduce acontact liquid 11, for example water of low surface tension, between thephotoresist layer 2 and the original, as represented in FIG. 1c. Withphotographic originals it is appropriate to harden the gelatine layerbeforehand and to choose a layer carrier of glass or polyester. Forprojections with conventional projectors, having separate ratios of, forexample, f 1/2.8, grating period of less than 1/500 mm are chosen, tothe extent possible. Regardless of the exposure technique used in anindividual case, the grating exposure in the method does not give riseto problems, since the whole grating image is produced on thephotoresist layer in one operation, and therefore, the exposure timemust only be set approximately so that the photolysis advances up to thelayer carrier.

During development, the exposed portion 6 of the photo layer 2 isdissolved away. A thin conductive layer having a thickness of about 0.1microns is applied to the structured residual photoresist layer, forexample by chemical deposition of palladium from a solution of palladiumchloride or by vapor-deposition of a metal such as silver. A minimumthickness of 50 μm of a metal, such as nickel, is electroplated ontothis layer and hence an embossed matrix is obtained for the informationcarrier, which is then separate from the photoresist layer afterelectroplating and forms an original negative of the structuredphotoresist layer 2'.

A thermoplastic film, preferably of polyvinyl chloride may be embossedwith this nickel matrix at an elevated temperature of about 130° C. andunder a pressure of several atmospheres/cm². The embossed film is aduplicate of the structured photoresist layer 2'. Since organicsubstances, such as polyvinyl chloride and photoresist, have almostidentical refractive indices n of about 1.5, the projection colors inboth cases are likewise almost identical. If the refractive indicesdiffer significantly from each other, the relief depths can be correctedin order to match the projection colors with each other. The result is aduplicate, which combines all the color separation images, and isembossed in a single operation.

The method produces good results if the thickness of the appliedphotoresist layers are very constant and if the single exposure throughto the given thickness of non-decomposed photoresist is carried out verycarefully. However, in practice it is found that the condition ofconstant thickness can only be met with difficulty.

In an alternative process, slight variations in thickness pose less of aproblem. In such a process, the exposure is effected in this case againby color separation, but the actinic light is screened, in the form of agrating, at the beginning. The starting point is, similarly, a stillunexposed photoresist layer 7 on a carrier 1, as represented in FIG. 2a.The thickness of the layer can have small variations, as indicated inFIG. 2a. The photoresist layer 7 is exposed through the color-separationoriginals 3, 4 and 5 with actinic light having a grating-like intensitydistribution. This exposure is checked continuously by measuring, sothat the exposure can be interrupted at exposure depths of about 1.26 μmat 13, 1.59 μm at 14 and 1.83 μm at 15. The result is a relief image 10'with a structured photoresist layer 7', illustrated in FIG. 2b. As wasexplained in the description of the first process, it is possible towork with separate color separations or with a combined colorseparation, the transmission values of which have approximately the samerelationships as the grating and relief depths in the various colorseparation areas. The exposures are carried out in a contact arrangementusing a contact liquid 11, or by projection with optical elements.Interfering laser light is preferred but an adequate grating-likeintensity modulation is also produced by color separation originals withgrating lines copied in, or with gratings in the path of the beam ofactinic light. The result is a relief image in the photoresist and,after the embossing, an information carrier which combines all the colorseparation images.

Single-color images will prove adequate for many reproductions. Thewhite parts correspond to grating-free areas of the image, that is tosay, areas without grating structures. An additional black colorseparation must be made for the black parts. The exposure through theblack color separation must be effected in such a way that the blackareas of the image appear as dark and colorless as possible whenprojected. With grating-type exposure, therefore, the duration of theexposure time must be so chosen that it does not produce strongprojection colors. The resulting relief depths are about 1 μm. The blackeffect is strengthened by a second, crosswise irradiated grating. Theprojection color usually varies between dark brown and dark lilac, withtransmission values which when averaged over the visible spectral range,can fall to values down to about five percent of the intensity of thefull light radiated in. Of course, complete color images also containblack and white parts.

EXAMPLE 2

A layer of positively-working photoresist having a thickness ofapproximately 3 μm is applied to a 5 cm×5 cm×0.2 cm large glass plate bywhirler-coating and drying. Successive exposures are then made for 35seconds, 25 seconds and 19 seconds through different color separationswhich are transparent at the areas of the image which are yellow,magenta-colored and cyan, respectively. After removal of the colorseparations, an exposure is made for 40 seconds under a metal grating,with 138 lines/mm, which is mounted on a glass plate. A drop of water oflow surface tension is introduced into the contact gap between the metalgrating and the photoresist to avoid interference effects. The exposureis carried out in a contact arrangement as has been already describedabove. The recording material is arranged in a copying frame, with thephotoresist layer facing the layer of the color separation originals,for the exposure under the color separation originals. A register markin the shape of a pair of straight lines at right-angles is, for examplescribed in the recording layer outside the image area for use duringalignment. The alignment of the individual color separation originalswith respect to the recording layer is effected under a microscope underyellow safelight with the aid of the register marks 12 on the originals(see FIG. 4). These marks are also included in the photographicproduction of the color separations. The color separation originalscontain relatively offset transparent areas of 5 mm diameter formeasuring purposes adjacent to the image area. These areas are likewiseirradiated with actinic light. In preliminary experiments it has beenfound that the light intensity behind the measuring areas must beincreased by a factor of about 2.75 for yellow, by a factor of about2.30 for magenta and by a factor of about 1.95 for cyan, in order toobtain the required relief depths This corresponds to exposure times of35 seconds, 25 seconds and 19 seconds, respectively. The exposedoriginal copy is rinsed with water and drops adhering to it are removedby dabbing it dry. Development is carried out with an aqueous alkalinedeveloper. Following this, a thin copper layer is vapor-deposited on therelief image and a deposit of nickel is electroplated on the copper. Apolyvinyl chloride film is embossed in a press at about 130° C. with thenickel matrix obtained. The relief image formed in the polyvinylchloride film by a single embossing produces a colored image in yellow,magenta and cyan on projection with an undiffracted beam.

EXAMPLE 3

Example 2 is repeated using four color separation originals, the fourthcolor separation original corresponding to the black image areas in thecolored original copy. Glass-clear, transparent areas 16 (see FIG. 3)are associated, at the appropriate positions, with the white image areasin all the color separations. The exposure under the black colorseparation is effected at up to a 3.1-fold increase of intensity behindthe relevant measuring area, for a period of 43 seconds.

In an undiffracted beam path, a projection image with yellow, magenta,cyan, white and black image areas is obtained from the finished reliefimage produced in one embossing operation. Careful examination has shownthat the black image areas rather correspond to a dark brown.

EXAMPLE 4

A 3 μm thick layer of positive-working photoresist is applied to a 50 μmthick glass-clear polyester film by whirler-coating and drying. Thephotoresist layer is exposed successively through different colorseparation originals for 67 seconds, 85 seconds and 95 seconds. One ofthe color separation originals is transparent to yellow, another tomagenta and a third to cyan positions on the image, and they are eachprovided with a grating structure. The exposure is effected in a contactarrangement by irradiation with actinic light, for example parallellight from a 200 watt mercury high-pressure lamp, through a quartz lensof focal length f=15 cm and through a blue glass filter with a maximumtransmission of 75% of wavelength of 400 nm. For exposure, the recordingmaterial with the layer facing a glass plate, is fixed to the plate,forming a pocket, using adhesive tape at the edge. A register mark inthe shape of a pair of straight lines at right angles is scribedbeforehand into the recording layer outside what will subsequently bethe image area for later alignment. The particular color separations areinserted into the said pocket, and, specifically, with the layer sidefacing the photoresist layer. The alignment into register of theoriginal and the recording material is effected in each case with amicroscope under yellow safelight. The aligned original is likewisefixed on the glass plate with adhesive tape, at a projecting end. Toproduce the color separation originals, a high-resolution silver film isexposed first in contact under a metal grating, which is located on aglass plate, and subsequently under a film negative of the correspondingcolor separation. The film negative has an alignment mark outside theimage area. Production of the color separation originals for the contactexposure requires particular care in order to obtain transparent areaswhich are glass-clear and non-transparent areas which cover as much aspossible without any blemishes. The specified exposure times aredetermined by measurement of the light intensity in preliminaryexperiments. After development with aqueous alkaline developer thesample is irradiated with white xenon light. A colored image of yellow,magenta and cyan is formed in the light passing through undiffracted,behind a projection optical element.

Under certain circumstances, the colored image shows interferencepatterns in the areas of color. In order to suppress this interference adrop of water of low surface tension is introduced into the contact gapbetween the post-hardened silver-film originals and the photoresist. Therequired exposure times are thereby reduced almost in half. Beforedeveloping, the exposed original copy is carefully rinsed with water anddrops adhering to it are removed by dabbing it. A thin copper layer isvapor-deposited on the photoresist layer which carries the relief imagecontaining all the color part-images, and a deposit of nickel iselectroplated on the copper to form a matrix.

A polyvinyl chloride film is embossed in a press, at approximately 130°C., with the nickel matrix obtained. The relief image, formed in thepolyvinyl chloride film by a single embossing operation, produces acolored image in yellow, magenta and cyan on projection in anundiffracted beam path.

EXAMPLE 5

Example 4 is repeated, using four color separation originals; the fourthcolor separation original corresponding to the black image areas in thecolored original copy image. The white image areas are opaque at therelevant positions in all the color separations. Depending on thedesired method of exposure, only the black positions are transparent onthe black color separation and are provided with an irradiated, crosseddouble grating. The exposure time under the black color separation is 35seconds. A projection image with yellow, magenta, cyan, white and blackimage parts is obtained, in undiffracted light, from the finished reliefimage produced by a single embossing.

The original copy or the information carrier, which contains, forexample, an image, data or the like, can, within the scope of theinvention, be any transparent material which can be embossed, evenmaterials composed of layers. This material can consist of anon-embossable, rigid or flexible, carrier layer with an embossablecover layer. The lowering of the viscosity, required for embossing, mustnot necessarily be effected only by an increase of temperature, but canalso be produced by the transitory action of solvents. A relief image isnormally viewed in the air. Under certain conditions, when necessary,the image can be coated in order to protect it from the surroundingenvironment. In order to provide, in spite of the coating, the sameoptical conditions as with a non-coated relief image, the refractiveindex of the coating material must be taken into account. For thispurpose it is necessary to specify the optical path length nd, where nis the refractive index and d the irradiated layer thickness. Thedifference between the optical path lengths at the relief grating shouldbe chosen according to d(n₁ -n₂), where d is the relief depth, n₁ is therefractive index of the relief material and n₂ is the refractive indexof the coating material. Organic materials generally have refractiveindices of about 1.5.

The information on the original copy is stored in areas on the film inthe form of alphanumeric symbols, lines or areas with gratings ofuniform grating depth, so-called relief structures, and the grating-likeinformation structures in turn can in the conventional manner, bescreened, for example to represent mixed colors. The areas can haveconnected information-structures as well as individual screen elements.

With screened images, the production of the color separation originals,as well as the alignment work is by its nature, particularly difficult.

The known screened structures have screen elements of about 10 μmdiameter. Such screen elements can be represented, for example, by aten-fold reduction of the 120 screen, customary in the printingindustry, with 120 screen elements/cm. Mounting is effected in this casewith the aid of register pins and holes up to accuracies of 1/200 mm. Aneffect which is observed particularly with screened informationstructures and which makes reproduction in color more difficult, is acolor shading which occurs at the edge of the screen point and which iscaused by a corresponding fall in the optical density of thephotographic original at the edge of the screen point. Re-copying theoriginal onto high-contrast silver film produces only a limitedimprovement. Relatively speaking, the best edge sharpness is obtainedwith metal images which are produced, for example, by coating apolyester film with an optically very dense aluminum layer having anoptical density of far above three, with a layer of positive photoresisthaving an approximate thickness of 1 micron, followed by exposure underthe screened original, and then development. The aluminum is etched awayat the exposed portions with aqueous iron-III chloride solution and thenthe remaining photoresist layer is dissolved away.

An identity carrier produced by embossing a deformable, transparentmaterial with the matrix is identical to the original copy if, in theembodiments of the original copy represented by drawing according toFIGS. 1d and 2b, a structured material, such as, for example, anembossed polyvinyl chloride film, is employed in place of the structuredphotoresist layer 2', 7'.

Although the invention has been described with respect to particularrecording materials, it should be understood that any of theconventional recording materials containing for example layers ofnegative-working photoresists with azido compositions or polyvinylcinnamate compositions may be used. Normal such recording materials havenot the same excellent edge sharpness as positive-working photoresists.

Likewise a wide range of deformable materials may be used to form copiesof the original information carrier. Thus, many materials which aredeformable and may be embossed under known methods, such as heat andpressure may be used. By way of example, some of these materials are:polyolefines such as polyethylene or non-stretched polyester.

The invention has been defined with reference to particular materials,layer thicknesses, light sources and the like. It should be understoodhowever that the invention is not limited to only the materials used,but extends to all equivalents and substitutes which may be used andthat the scope of the invention is limited only by the claims.

What is claimed is:
 1. A process for producing an original of aninformation carrier for use in zero order diffraction color projectionwhich comprises the steps of:(a) exposing a recording layer, mounted ona carrier, through separate color separation originals to form reliefpart-images, each relief part-image corresponding to a differentprojection color, said originals being transparent in the areas of theparticular projection colors of the individual color separationoriginals each of said relief part-images of the projection coloradjoining one another without overlap and having a depth correspondingto one of the particular projection colors; (b) exposing the entireportion of said recording layer to be utilized in carrying informationto a grating pattern without intervening development to provide astructure in which the recording layer is exposed through to saidcarrier; (c) said image-wise exposure through each individual colorseparation original provided with an energy density equal to thatrequired to obtain the individual projection color; and (d) developingsaid exposed recording layer.
 2. The process as defined by claim 1,wherein said exposure of step (a) is carried out through the individualcolor separation originals for different lengths of time.
 3. The processas defined by claim 1, wherein said exposure of step (a) occurs beforesaid exposure of step (b).
 4. The process as defined by claim 1, whichcomprises photochemically degrading said recording layer during theexposure steps.
 5. The process as defined by claim 4, wherein after theexposure of said recording layer during step (a), the recording layer isexposed over its entire surface down through to said carrier materialwith a grating pattern.
 6. The process as defined by claim 1, whereinsaid exposure of step (b) is performed prior to said exposure of step(a).
 7. The process as defined by claim 1, wherein steps (a) and (b) arecombined for simultaneously exposing said recording layer to said colorseparation originals and said grating pattern.
 8. The process as definedin claim 7, which comprises selecting the transmission parameters ofsaid color separation original to correspond to preselected reliefdepths.
 9. The process as defined by claim 1 or 7, which comprisescarrying said grating exposure by passing laser beams having a linespacing corresponding to a grating pattern over said recording layer sothat they interfere with one another; and modulating said laser beams totransmit information to said recording layer.
 10. The process as definedby claim 1, which comprises forming said grating pattern of step (b) bymodulating a light beam from a light source by means of gratings locatedin the path of said beam.
 11. The process as defined by claim 1, whereinsaid grating exposure is obtained by means of color separation originalshaving a grating pattern which is copied thereon.
 12. The process asdefined by claim 1, which comprises arranging said color separationoriginals such that they contact said recording layer while saidrecording layer is being exposed.
 13. The process as defined by claim 1,which comprises introducing a colorless contact liquid into a contactzone located between said recording layer and said color separationoriginals.
 14. The process as defined by claim 1, which comprises usingmetal images as said separation originals.
 15. The process as defined byclaim 1, which comprises developing said recording layer under aqueousalkaline conditions.